The proposed project is designed to develop and validate a physiological, brain-based measure of prejudice. This measure, which relies on event-related brain potentials (ERPs), has been used frequently in the general attitudes domain, where its sensitivity to attitude valence and degree of extremity has been demonstrated. The proposed research will modify this existing paradigm to assess ERP reliability as a measure of individual differences in attitudes toward social groups, its relation to behavior, and the extent to which it relates to extant implicit and explicit measures of prejudice and stereotyping. Concern about the reactivity of self-report measures has fueled development of implicit measures of prejudice and stereotyping. The proposed research represents an important step to expanding our range of measures to include physiological ones. ERPs have several unique and advantageous features relative to implicit measures. Whereas implicit measures are by definition indirect measures, the ERP is a direct, on-line measure of information processing activities. ERPs are also sensitive to the underlying evaluative percept itself, even when this evaluation is inconsistent with explicit verbal reports. Recent research also reveals that ERPs are sensitive not only to intentional evaluations, but also to more spontaneously activated evaluative judgments. Thus, ERPs may be useful in marking early evaluative responses that an individual may not even intend. The development of an ERP measure of prejudice may therefore aid in our understanding of prejudice, especially with respect to how a single social group can produce different and sometimes conflicting evaluative dispositions depending on the type of measure being used.